The present invention relates in general to ship cranes and in particular to a new and useful method and apparatus of controlling the horizontal motion of a double articulated crane.
The steadily increasing volume of container cargo shipping makes a further devleopment of shipboard handling systems imperative to reduce turnaround times in ports and simplify the handling of goods. Experience with conventional shipboard crane constructions have led to a development of new loading systems. What was sought were primarily optimum vision conditions for the crane operator, a faster and more accurate control of load movements, and smaller overall heights of the cranes, to improve the vision from the bridge.
A new kind of shipboard crane has been developed in this direction, namely so called articulated cranes having their boom comprised of a base section or member, and a head member. The base member is pivotable as an arm on the crane post, and the base and head members cooperate in the manner of an elbow joint.
A prior art control for the drives of handling equipment, particularly a ship crane, provides a loading tackle at the end of a hinged boom, and controlled drives for at least one sluing, hoisting and/or traveling gear. The drives are equipped with controllers having their desired value inputs connected to transmitters of a model-loader, by which the desired sequential movements are picked up and transmitted as desired values to the control, and the end of the model boom is guided by means of a guide body in a base plate, with the guide body being operatively connected to a drive. The speed of the drive is adjustable by a setting member having a setting handle. The path of motion of the base joint of the model boom is adjustable in order to adapt to varying distances (German OS No. 28 06 399).
Such a control has the disadvantage of being very expensive. A special model is required, for example. Further, the pickup or unloading points can be reached only in a straight-line approach, i.e. sequentially by following coordinates of the target point.